The present invention relates to sulfonylureas of the general 5 formula I 
where
R1 is a methyl or ethyl group;
R2 is C1-C3-alkoxycarbonyl, a C1-C2-alkyl group which carries 1 to 5 fluorine atoms, methylsulfonyl, dimethylaminosulfonyl, thiomethyl, methylsulfinyl, methylsulfonyloxy, trifluoromethoxy, difluoromethoxy, difluorochloromethoxy, difluorochloromethyl or nitro;
R3 is hydrogen, methyl, methoxy, ethoxy, fluorine, chlorine or thiomethyl;
W is hydrogen or chlorine and
Z is CH or N
and their agriculturally utilizable salts.
In U.S. Pat. No. 4,120,691, the nearest structures described are the triazine compound A and the pyrimidine derivative B (cf. also U.S. Pat. No. 4,169,719). 
In EP-A 48 808, sulfonylureas D having a substituent in the aromatic moiety are described. 
Z=CH or N
In EP-A 48 143, two N-methylated sulfonylureas E are shown without closer characterization. 
Z=CH or N
EP-A 388 873 covers benzoic acid esters of the structure F. 
R=CH3 or C2H5 
In U.S. Pat. No. 4,310,346, sulfonamides of the type G are listed. 
Z=CH or N
German Laid-Open Application DE-OS 40 38 430 (WO 92/09608) describes trifluoromethyl-substituted triazines of type H. 
R=halogen, CF3, alkylsulfonyl or O(CH2)2OCH3 
EP-A 120 814 mentions the compound J without details of physical data. 
It is an object of the present invention to synthesize sulfonylureas which, compared with the known representatives of this class of herbicide, have improved properties and are particularly distinguished by high selectivity in sensitive crops.
We have now found that this object can be achieved by the sulfonylureas of the formula I defined at the outset.
In the formula I, C1-C3-alkoxycarbonyl is methoxycarbonyl, ethoxycarbonyl, n-propoxycarbonyl or isopropoxycarbonyl and a C1-C2-alkyl group which carries 1 to 5 fluorine atoms is methyl, substituted by 1 to 3 fluorine atoms, or ethyl, substituted by 1 to 5 fluorine atoms, eg. trifluoromethyl, difluoromethyl, 2,2,2-trifluoroethyl or 1,1,2,2-tetrafluoroethyl.
Sulfonylureas of the formula I are particularly preferred in which R2 is methoxycarbonyl, trifluoromethyl, dimethylaminosulfonyl, trifluoromethoxy, difluoromethoxy or methylsulfonyl, and also sulfonylureas having a triazine substituent (Z=N). Compounds I with difluoromethyl substitution of hetero atoms (W=H) are additionally particularly important.
The sulfonylureas of the formula I according to the invention are accessible by various routes which are described in the literature. By way of example, particularly advantageous routes (A-C) may be illustrated in greater detail in the following. 
A:
A sulfonyl isocyanate II is reacted in a manner known per se (EP-A-162 723) with approximately the stoichiometric amount of a 2-amino-1,3,5-triazine or 2-aminopyrimidine derivative III at from 9 to 120xc2x0 C., preferably from 10 to 100xc2x0 C. The reaction can be carried out continuously under normal pressure or under pressure (up to 50 bar), preferably at from 1 to 5 bar.
Inert solvents and diluents are expediently used for the reactions under the respective reaction conditions. Suitable solvents are, for example, halohydrocarbons, in particular chlorohydrocarbons, eg. tetrachloroethylene, 1,1,1,2- or 1,1,2,2-tetrachloroethane, dichloropropane, methylene chloride, dichlorobutane, chloroform, chloronaphthalene, dichloronaphthalene, carbon tetrachloride, 1,1,1- or 1,1,2-trifluoroethane, trichloroethylene, pentachloroethane, o-, m- or p-difluorobenzene, 1,2-dichloroethane, 1,1-dichloroethane, 1,2-cis-dichloroethylene, chlorobenzene, fluorobenzene, bromobenzene or iodobenzene, o-, m- or p-dichlorobenzene, o-, p- or m-dibromobenzene, o-, m- or p-chlorotoluene, 1,2,4-trifluorobenzene; ethers, eg. ethyl propyl ether, methyl tert-butyl ether, n-butyl ethyl ether, di-n-butyl ether, diisobutyl ether, diisoamyl ether, diisopropyl ether, anisole, phenetole, cyclohexyl methyl ether, diethyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, dioxane, thioanisole or xcex2,xcex2xe2x80x2-dichlorodiethyl ether, nitrohydrocarbons such as nitromethane, nitroethane, nitrobenzene, o-, m- or p-chloronitrobenzene or o-nitrotoluene; nitriles such as acetonitrile, butyronitrile, isobutyronitrile, benzonitrile or m-chlorobenzonitrile; aliphatic or cycloaliphatic hydrocarbons, eg. heptane, pinane, nonane, or o-, m- or p-cymene, benzene fractions within a boiling point range from 70 to 190xc2x0 C., cyclohexane, methylcyclohexane, decalin, petroleum ether, hexane, naphtha, 2,2,4-trimethylpentane, 2,2,3-trimethylpentane, 2,3,3-trimethylpentane or octane; esters, eg. ethyl acetate, ethyl acetoacetate or isobutyl acetate; amides, eg. formamide, methylformamide or dimethylformamide; ketones, eg. acetone or methyl ethyl ketone, and suitable mixtures. The solvent is expediently used in an amount of from 100 to 2000% by weight, preferably from 200 to 700% by weight, based on the starting substance II.
The compound II required for the reaction is in general employed in approximately equimolar amounts (using an excess or deficit of eg. 0 to 20%, based on the respective starting substance III). The starting substance III can be introduced in one of the diluents mentioned and the starting substance II then added.
The process for preparing the novel compounds is expediently carried out, however, such that the starting substance II is introduced, if appropriate in one of the abovementioned diluents, and the starting substance III is then added.
To complete the reaction, the mixture is subsequently stirred after the addition of the components for a further 20 minutes to 24 hours at from 0 to 120xc2x0 C., preferably from 10 to 100xc2x0 C.
A reaction accelerator which can be used is advantageously a tertiary amine, eg. pyridine, xcex1, xcex2 or xcex3-picoline, 2,4- or 2,6-lutidine, 2,4,6-collidine, p-dimethylaminopyridine, trimethylamine, triethylamine, tri(n-propyl)amine, 1,4-diaza[2.2.2]bicyclooctane [DABCO] or 1,8-diazabicyclo[5.4.0]undec-7-ene in an amount of from 0.01 to 1 mol per mole of starting substance II.
The final substance I is isolated from the reaction mixture in a customary manner, eg. by removal of solvent by distillation or directly by filtering off with suction. The residue which remains can additionally be washed with water or dilute acid to remove basic impurities. However, the residue can also be dissolved in a water-immiscible solvent and washed as described. The desired final substances are obtained here in pure form. If necessary they can be purified by recrystallization, stirring in an organic solvent which takes up the impurities or chromatography.
Preferably, this reaction is carried out in acetonitrile, methyl tert-butyl ether, toluene or methylene chloride in the presence of from 0 to 100 mol equivalents, preferably from 0 to 50 mol equivalents, of a tertiary amine such as 1,4-diaza-bicyclo[2.2.2]octane or triethylamine.
B:
A sulfonamide of the formula IV is reacted in a manner known per se (EP-A 141 777 or EP-A 101 670) in an inert organic solvent with approximately the stoichiometric amount of a phenyl carbamate V and from 0 to 120xc2x0 C., preferably from 20 to 100xc2x0 C. The reaction can be carried out continuously or batchwise at normal pressure or under pressure (up to 50 bar), preferably at from 1 to 5 bar.
Bases such as tertiary amines can be added here which accelerate the reaction and improve the product quality. Suitable bases for this purpose are those indicated under A, in particular triethylamine, 2,4,6-collidine, 1,4-diazabicyclo[2.2.2]octane [DABCO] or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), in an amount of from 0.01 to 1 mol per mole of starting substance IV.
The solvents or diluents expediently used are those indicated under A.
The solvent is used in an amount of from 100 to 2000% by weight, preferably from 200 to 700% by weight, based on the starting material IV.
The compound IV required for the reaction is in general employed in approximately equimolar amounts (using an excess or deficit of eg. from 0 to 20%, based on the respective starting substances V). The starting substance V can be introduced into one of the abovementioned diluents and the starting substance IV then added.
However, the starting substance IV can also be introduced into one of the solvents mentioned and the carbamate V then added. In both cases one of the bases mentioned can be added as a catalyst before or during the reaction.
To complete the reaction, the mixture is subsequently stirred after the addition of the components for a further 20 minutes to 24 hours at from 0 to 120xc2x0 C., preferably from 10 to 100xc2x0 C., in particular from 20 to 80xc2x0 C.
The sulfonylureas of the formula I are isolated from the reaction mixture using the customary methods, such as described under A.
C:
A sulfonamide of the formula IV is reacted in a manner known per se (EP-A 234 352) in an inert organic solvent with approximately the stoichiometric amount of an isocyanate VI at from 0 to 150xc2x0 C., preferably from 10 to 100xc2x0 C. The reaction can be carried out continuously or batchwise at normal pressure or under pressure (up to 50 bar), preferably at from 1 to 5 bar.
Before or during the reaction, bases such as tertiary amines can be added here which accelerate the reaction and improve the product quality. Suitable bases for this purpose are those indicated under A, in particular triethylamine or 2,4,6-collidine, in an amount of from 0.01 to 1 mol per mole of starting substance IV.
The solvents used are expediently those indicated under A. The solvent is employed in an amount of from 100 to 2000% by weight, preferably of 200 to 700% by weight, based on the starting material IV.
The compound IV required for the reaction is in general employed in approximately equimolar amounts (using an excess or deficit of eg. from 0 to 20%, based on the starting materials VI). The starting substance VI can be initially introduced into one of the diluents mentioned and the starting substance IV then added. However, the sulfonamide can also be initially introduced and the isocyanate VI then added.
To complete the reaction, the mixture is stirred after the addition of the components for a further 20 minutes to 24 hours at from 0 to 120xc2x0 C., preferably from 10 to 100xc2x0 C., in particular from 20 to 80xc2x0 C. The final product I can be obtained from the reaction mixture in the customary manner, as described under A:.
The sulfonyl isocyanates of the formula II required as starting substances can be obtained from the corresponding sulfonamides by phosgenation in a manner known per se (Houben-Weyl 11/2 (1985) 1106, U.S. Pat. No. 4,379,769) or by reaction of the sulfonamides with chlorosulfonyl isocyanate (DE-A 31 32 944).
Carbamates of the formula V are accessible by or in a similar manner to known reactions (eg. EP-A 101 670); however, they can also be prepared from the corresponding isocyanates VI by reaction with phenol.
The isocyanates of the formula VI are obtained from the amines of the formula III by treatment with oxalyl chloride or phosgene (in a similar manner to Angew. Chem. 83 (1971) 407, EP-A 388 873).
The sulfonamides can be obtained by reaction of the corresponding sulfonyl chlorides with ammonia (Houben-Weyl, Methoden der organischen Chemie (Methods of organic chemistry), Volume 9 (1955) 605). The sulfonyl chlorides are obtained by Meerwein reaction (diazotization of suitable amines and copper salt-catalyzed sulfochlorination). 2-Amino-4-chlorodifluoromethyl-6-methoxy-1,3,5-triazine and 2-amino-4-difluoromethyl-6-methoxy-1,3,5-triazine can be synthesized as illustrated in the preparation example. The corresponding 6-ethoxy-substituted 1,3,5-triazines can be prepared in a similar manner.
The corresponding pyrimidines of the general formula III are accessible by the following sequence: 
Corresponding reactions are well known (D. J. Brown in xe2x80x9cThe Chemistry of Heterocyclic Compoundsxe2x80x9d, Interscience Publishers, New York, London, Vol. 14, Heterocycl. Chem. 20 (1983) 219).
The compounds I can be present in the form of their agriculturally utilizable salts, where in general the nature of the salt does not matter. Customarily, the salts of those bases will be suitable which do not adversely affect the herbicidal action of I.
The salts of the compounds I are accessible in a manner known per se (EP-A-304 282, U.S. Pat. No. 4,599,412). They are obtained by deprotonation of the corresponding sulfonylureas I in water or an inert organic solvent at from xe2x88x9280xc2x0 C. to 120xc2x0 C., preferably from 0xc2x0 C. to 60xc2x0 C., in the presence of a base.
Suitable bases are, for example, alkali metal or alkaline earth metal hydroxides, hydrides, oxides or alkoxides such as sodium, potassium and lithium hydroxide, sodium methoxide, ethoxide and tert-butoxide, sodium and calcium hydride and calcium oxide. Salts of transition metals, preferably manganese, copper, zinc and iron salts and also the ammonium salts which can carry one to three C1-C4-alkyl or hydroxy-C1-C4-alkyl substituents and/or a phenyl or benzyl substituent, preferably diisopropylammonium, tetramethylammonium, tetrabutylammonium, trimethylbenzylammonium and trimethyl(2-hydroxyethyl)ammonium salts, the phosphonium salts, the sulfonium salts, preferably tri-(C1-C4)-alkylsulfonium salts, and the sulfoxonium salts, preferably tri-(C1-C4)-alkylsulfoxonium salts can also be employed as basic salts.
In addition to water, suitable solvents, for example, are also alcohols such as methanol, ethanol and tert-butanol, ethers such as tetrahydrofuran and dioxane, acetonitrile, dimethylformamide, ketones such as acetone and methyl ethyl ketone and also halogenated hydrocarbons.
Deprotonation can be carried out at normal pressure or at pressures of up to 50 bar, preferably at normal pressure up to an excess pressure of 5 bar.
The compounds I or the herbicidal compositions containing them and their environmentally tolerable salts of alkali metals and alkaline earth metals can very effectively control weeds in crops such as wheat, rice and maize without damaging the crop plants, an effect which occurs especially even at low application rates. They can be applied by spraying, atomizing, dusting, broadcasting or watering in the form of directly sprayable solutions, powders or suspensions, even high-percentage aqueous, oily or other suspensions, or dispersions, emulsions, oil dispersions, pastes, dusting compositions, broadcasting compositions or granules. The application forms depend on the intended use; in each case they should if possible guarantee the finest dispersion of the active compounds according to the invention.
The compounds I are generally suitable for preparing directly sprayable solutions, emulsions, pastes or oil dispersions. Suitable inert additives are, inter alia, mineral oil fractions of medium to high boiling point, such as kerosene or diesel oil, and also coal tar oils and oils of vegetable or animal origin, aliphatic, cyclic and aromatic hydrocarbons, eg. toluene, xylene, paraffin, tetrahydronaphthalene, alkylated naphthalenes or their derivatives, methanol, ethanol, propanol, butanol, cyclohexanol, cyclohexanone, chlorobenzene, isophorone or strongly polar solvents, such as N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone or water.
Aqueous application forms can be prepared from emulsion concentrates, dispersions, pastes, wettable powders or water-dispersible granules by addition of water. To prepare emulsions, pastes or oil dispersions, the substrates as such or dissolved in an oil or solvent can be homogenized in water by means of wetting agents, adhesives, dispersants or emulsifiers. However, concentrates consisting of active substance, wetting agent, adhesive, dispersant or emulsifier and possibly solvent or oil can be prepared, which are suitable for dilution with water.
Suitable surface-active substances are the alkali metal, alkaline earth metal and ammonium salts of aromatic sulfonic acids, eg. lignosulfonic, phenolsulfonic, naphthalenesulfonic and dibutylnaphthalenesulfonic acid, and of fatty acids, alkyl- and alkylrylsulfonates, alkyl-, lauryl ether and fatty alcohol sulfates, as well as salts of sulfated hexa-, hepta- and octadecanols, and also of fatty alcohol glycol ethers, condensation products of sulfonated naphthaline and its derivatives with formaldehyde, condensation products of naphthalene or of naphthalenesulfonic acids with phenol and formaldehyde, polyoxyethylene octylphenol ether, ethoxylated isooctyl-, octyl- or nonylphenol, alkylphenol or tributylphenyl polyglycol ethers, alkylaryl polyether alcohols, isotridecyl alcohol, fatty alcohol/ethylene oxide condensates, ethoxylated castor oil, polyoxyethylene or polyoxypropylene alkyl ethers, lauryl alcohol polyglycol ether acetate, sorbitol esters, lignin-sulfite waste liquors or methylcellulose.
Powder, broadcasting and dusting compositions can be prepared by mixing or joint grinding of the active substances with a solid carrier.
Granules, eg. coated, impregnated and homogeneous granules can be prepared by binding the active compounds to solid carriers. Solid carriers are mineral earths such as silicic acids, silica gels, silicates, talc, kaolin, limestone, lime, chalk, bole, loess, clay, dolomite, diatomaceous earth, calcium sulfate and magnesium sulfate, magnesium oxide, ground synthetic materials, fertilizers, such as ammonium sulfate, ammonium phosphate, ammonium nitrate, ureas and vegatable products, such as cereal meal, tree bark meal, wood meal and nut shell meal, cellulose powder or other solid carriers.
The formulations in general contain from 0.1 to 95% by weight, preferably from 0.5 to 90% by weight, of active compound. The active compounds are employed here in a purity of from 90 to 100%, preferably from 95 to 100% (according to NMR spectrum).